1. Technical Field
The invention relates to a method of manufacturing a semiconductor device. More specifically, the invention relates to a method of manufacturing a semiconductor device including a memory cell.
2. Related Art
A memory device is classified into a volatile memory device and a nonvolatile memory device based on maintenance of data when a power supply cuts off. The volatile memory device is a memory device, from which data is erased when the power supply cuts off, and a DRAM and an SRAM are included therein. The nonvolatile memory device is a memory device, which maintains stored data although the power supply cuts off, and includes a flash memory device.
The nonvolatile memory element is mainly used in a portable electronic device such as a cellular phone, a digital camera, an MP3 player, and/or the like, and is required to improve a driving speed and increase a storage capacity of the memory device by the miniaturization and high capacity tendency of a recent portable electronic device. Also, in order to improve reliability of stored data, a method for improving data retention characteristics is required.